1. Field of the Invention
The invention relates generally to direct current motors and more particularly to an electronically commutated, collectorless direct current motor having a multipolar, permanent magnet rotor and a multipart, multipolar stator winding wound on an insulating body surrounding the rotor.
2. Description of the Prior Art
In the field of rotating machinery, a direct current motor of the type described herein is known. A discussion of such a motor may be found in the German publication "Elektronikmotor DM.sub.c 3, ein neuer Kollektorloser Gleichstromkleinst Motor," Siemens-- Zeitschrift, September, 1966, pp. 690-693. This prior art direct current motor was intended to be employed to drive battery powered devices such as portable tape records. In these drive motors, emphasis is placed primarily upon rotational speed stability during operation of the battery powered device. Note that electronically commutated direct current motors are presently being employed to an increasing degree in the field of data processing. The direct current motors employed for this application must be electronically commutated and must display good dynamic properties. Those properties include low rotor inertia which results in short starting and braking times while offering the highest possible operating torque.
A problem exists in that the prior art direct current motor does not possess the characteristics described herein. The prior art motor has a solid rotor leading to relatively poor dynamic operating properties. Further, because of weak magnetic coupling between the stator winding and the stator core, the motor has a relatively low efficiency factor.